Let's roll up our sleeves and solve this. We have 790 and we're going to multiply it by 131, essentially adding 790 to itself 131 times.
Step 1: 0 + 790 = 790
Step 2: 790 + 790 = 1580
Step 3: 1580 + 790 = 2370
Step 4: 2370 + 790 = 3160
Step 5: 3160 + 790 = 3950
Step 6: 3950 + 790 = 4740
Step 7: 4740 + 790 = 5530
Step 8: 5530 + 790 = 6320
Step 9: 6320 + 790 = 7110
Step 10: 7110 + 790 = 7900
Step 11: 7900 + 790 = 8690
Step 12: 8690 + 790 = 9480
Step 13: 9480 + 790 = 10270
Step 14: 10270 + 790 = 11060
Step 15: 11060 + 790 = 11850
Step 16: 11850 + 790 = 12640
Step 17: 12640 + 790 = 13430
Step 18: 13430 + 790 = 14220
Step 19: 14220 + 790 = 15010
Step 20: 15010 + 790 = 15800
Step 21: 15800 + 790 = 16590
Step 22: 16590 + 790 = 17380
Step 23: 17380 + 790 = 18170
Step 24: 18170 + 790 = 18960
Step 25: 18960 + 790 = 19750
Step 26: 19750 + 790 = 20540
Step 27: 20540 + 790 = 21330
Step 28: 21330 + 790 = 22120
Step 29: 22120 + 790 = 22910
Step 30: 22910 + 790 = 23700
Step 31: 23700 + 790 = 24490
Step 32: 24490 + 790 = 25280
Step 33: 25280 + 790 = 26070
Step 34: 26070 + 790 = 26860
Step 35: 26860 + 790 = 27650
Step 36: 27650 + 790 = 28440
Step 37: 28440 + 790 = 29230
Step 38: 29230 + 790 = 30020
Step 39: 30020 + 790 = 30810
Step 40: 30810 + 790 = 31600
Step 41: 31600 + 790 = 32390
Step 42: 32390 + 790 = 33180
Step 43: 33180 + 790 = 33970
Step 44: 33970 + 790 = 34760
Step 45: 34760 + 790 = 35550
Step 46: 35550 + 790 = 36340
Step 47: 36340 + 790 = 37130
Step 48: 37130 + 790 = 37920
Step 49: 37920 + 790 = 38710
Step 50: 38710 + 790 = 39500
Step 51: 39500 + 790 = 40290
Step 52: 40290 + 790 = 41080
Step 53: 41080 + 790 = 41870
Step 54: 41870 + 790 = 42660
Step 55: 42660 + 790 = 43450
Step 56: 43450 + 790 = 44240
Step 57: 44240 + 790 = 45030
Step 58: 45030 + 790 = 45820
Step 59: 45820 + 790 = 46610
Step 60: 46610 + 790 = 47400
Step 61: 47400 + 790 = 48190
Step 62: 48190 + 790 = 48980
Step 63: 48980 + 790 = 49770
Step 64: 49770 + 790 = 50560
Step 65: 50560 + 790 = 51350
Step 66: 51350 + 790 = 52140
Step 67: 52140 + 790 = 52930
Step 68: 52930 + 790 = 53720
Step 69: 53720 + 790 = 54510
Step 70: 54510 + 790 = 55300
Step 71: 55300 + 790 = 56090
Step 72: 56090 + 790 = 56880
Step 73: 56880 + 790 = 57670
Step 74: 57670 + 790 = 58460
Step 75: 58460 + 790 = 59250
Step 76: 59250 + 790 = 60040
Step 77: 60040 + 790 = 60830
Step 78: 60830 + 790 = 61620
Step 79: 61620 + 790 = 62410
Step 80: 62410 + 790 = 63200
Step 81: 63200 + 790 = 63990
Step 82: 63990 + 790 = 64780
Step 83: 64780 + 790 = 65570
Step 84: 65570 + 790 = 66360
Step 85: 66360 + 790 = 67150
Step 86: 67150 + 790 = 67940
Step 87: 67940 + 790 = 68730
Step 88: 68730 + 790 = 69520
Step 89: 69520 + 790 = 70310
Step 90: 70310 + 790 = 71100
Step 91: 71100 + 790 = 71890
Step 92: 71890 + 790 = 72680
Step 93: 72680 + 790 = 73470
Step 94: 73470 + 790 = 74260
Step 95: 74260 + 790 = 75050
Step 96: 75050 + 790 = 75840
Step 97: 75840 + 790 = 76630
Step 98: 76630 + 790 = 77420
Step 99: 77420 + 790 = 78210
Step 100: 78210 + 790 = 79000
Step 101: 79000 + 790 = 79790
Step 102: 79790 + 790 = 80580
Step 103: 80580 + 790 = 81370
Step 104: 81370 + 790 = 82160
Step 105: 82160 + 790 = 82950
Step 106: 82950 + 790 = 83740
Step 107: 83740 + 790 = 84530
Step 108: 84530 + 790 = 85320
Step 109: 85320 + 790 = 86110
Step 110: 86110 + 790 = 86900
Step 111: 86900 + 790 = 87690
Step 112: 87690 + 790 = 88480
Step 113: 88480 + 790 = 89270
Step 114: 89270 + 790 = 90060
Step 115: 90060 + 790 = 90850
Step 116: 90850 + 790 = 91640
Step 117: 91640 + 790 = 92430
Step 118: 92430 + 790 = 93220
Step 119: 93220 + 790 = 94010
Step 120: 94010 + 790 = 94800
Step 121: 94800 + 790 = 95590
Step 122: 95590 + 790 = 96380
Step 123: 96380 + 790 = 97170
Step 124: 97170 + 790 = 97960
Step 125: 97960 + 790 = 98750
Step 126: 98750 + 790 = 99540
Step 127: 99540 + 790 = 100330
Step 128: 100330 + 790 = 101120
Step 129: 101120 + 790 = 101910
Step 130: 101910 + 790 = 102700
Step 131: 102700 + 790 = 103490

So, 790*131 = 103490